Header lift system for harvesters

ABSTRACT

A pull-type mower conditioner includes a crop harvesting header vertically movable relative to the frame of the mower conditioner between a raised transport position and a lowered operative position, a lift mechanism to effect the movement of the crop harvesting header relative to the frame, and a transport latch mechanism to control the locking of the lift mechanism in the transport position. The lift linkage incorporates a cam mechanism that serves as an upper flotation limit under normal operating conditions and automatically converts into a device for securing the header in the transport position when the header is moved into the transport position.

This application is a division of U.S. patent application Ser. No.08/673,677, filed Jun. 25, 1996, now U.S. Pat. No. 5,806,291, which is acontinuation of Provisional Application No. 60/000,817, filed Jun. 26,1995.

CROSS-REFERENCE TO RELATED APPLICATIONS BACKGROUND OF THE INVENTION

This invention relates generally to a pull-type machine for harvestingcrops from a field and, more particularly, to a lift linkage thatdefines header flotation limits and that can be secured for transportpurposes.

Trailed harvesting implements, such as mower conditioners, with liftsystems that are positioned with one or more hydraulic cylinders,require a mechanical device for positively locking the implement in theraised position to insure that during transport on the highway theimplement will not lower due to a hydraulic leak or failure. It isdesirable that a mechanism be provided to permit the operator to engagea lever before getting onto the tractor to start operation of thetractor and harvesting implement so that the locking device willautomatically engage when the implement is raised into the transportposition. It is also preferable that the mechanism bias the lockingdevice in the locked position.

It would be further preferable that the same mechanism permit theoperator, having arrived at the field, to engage the mechanism beforegetting into the tractor so that the locking mechanism will unlock whenthe implement is raised fully, thereby allowing the operator to commenceuse of the implement without again dis-mounting from the tractor tounlock the locking device. It would also be desirable that the mechanismalso hold the locking device in the unlocked position such that thelocking device will not engage when the implement is raised during fieldoperation to clear the cut crop or an obstacle.

Crop harvesting headers are suspended from the harvester frame forflotational movement relative thereto. It is desirable to provide adevice to define the range of operation for the flotational movement ofthe header. It is further desirable that the flotation limit beconvertible to secure the header when in the transport position toprevent the header from bouncing during transportation thereof over theground and, thereby, contacting other structural components of theharvester and effecting damage thereof.

SUMMARY OF THE INVENTION

It is an object of this invention to overcome the aforementioneddisadvantages of the prior art by providing a lift linkage that definesan operating range for header flotation movement.

It is a feature of this invention that the lift linkage includes a cammechanism that is rotatable when the lift linkage moves to the transportposition to convert from an upper flotation limit to a device forsecuring the header in the transport position.

It is an advantage of this invention that the cam mechanismautomatically converts from an upper flotation stop to a device forsecuring the header in the transport position when the header is raisedto the transport position.

It is another object of this invention to provide a lift linkage thatserves to secure the header while in the transport position.

It is still a further object of this invention to provide a lift linkagefor a pull-type harvesting implement which is durable in construction,inexpensive of manufacture, carefree of maintenance, facile inassemblage, and simple and effective in use.

These and other objects, features and advantages are accomplishedaccording to the instant invention by providing a pull-type mowerconditioner having a crop harvesting header vertically movable relativeto the frame of the mower conditioner between a raised transportposition and a lowered operative position, a lift mechanism to effectthe movement of the crop harvesting header relative to the frame, and atransport latch mechanism to control the locking of the lift mechanismin the transport position. The lift linkage incorporates a cam mechanismthat serves as an upper flotation limit under normal operatingconditions and automatically converts into a device for securing theheader in the transport position when the header is moved into thetransport position.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of this invention will be apparent upon consideration ofthe following detailed disclosure of the invention, especially whentaken in conjunction with the accompanying drawings wherein:

FIG. 1 is a top plan view of a disc mower conditioner incorporating theprinciples of the instant invention, the conventional draft tongue andPTO shaft being broken off for purposes of clarity;

FIG. 2 is a cross-sectional view of the disc mower conditioner takenalong lines 2--2 of FIG. 1 to depict a right side elevational view ofthe disc mower conditioner;

FIG. 3 is an enlarged partial cross-sectional view of the disc mowerconditioner taken along lines 3--3 of FIG. 2 to depict a top plan viewof the transport latch mechanism incorporating the principles of theinstant invention, the movement of the biasing lever into the lockingposition being shown in phantom;

FIG. 4 is a partial side elevational view of the disc mower conditionerwith the header being lowered to the operating position and thetransport latch being biased into the locking position, the movement ofthe biasing lever into the unlocking position being shown in phantom;

FIG. 5 is a partial side elevational view of the mower conditionersimilar to that of FIG. 4 but with the header being raised into thetransport position, the movements of the frame of the mower conditionerrelative to the header while the header is being raised into thetransport position;

FIG. 6 is a partial side elevational view of the mower conditionersimilar to that of FIG. 5, the relative movement of the frame andtransport latch to lock the header into the raised transport positionbeing shown in phantom;

FIG. 7 is a top plan view of a center pivot harvester incorporating theprinciples of the instant invention, the tongue being broken off forpurposes of clarity, portions of the header structure being broken awayto better shown the header support arm structure, the swinging movementsof the draft tongue being shown in phantom;

FIG. 8 is an enlarged partial top plan view of the harvester depictingthe left header support arm as shown in FIG. 7;

FIG. 9 is a partial rear elevational view of the left header support armshown in FIG. 8;

FIG. 10 is a schematic side elevational view of the harvester shown inFIG. 7 with the header in the lowermost operating position with thelower flotation limit engaged;

FIG. 11 is a schematic side elevational view similar to that of FIG. 10but with the header moved to the uppermost flotation position engagingthe upper flotation limit, the lowermost flotation position, as depictedin FIG. 10, being shown in phantom; and

FIG. 12 is a schematic side elevational view similar to that of FIGS. 10and 11, but with the header moved into the transport position whicheffects a substantially simultaneous engagement of both the top andbottom flotation limits.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings and, particularly, to FIGS. 1 and 2, thedisc mower conditioner utilizing a modular disc cutterbar andincorporating the principles of the instant invention can best be seen.Left and right references are used as a matter of convenience and aredetermined by standing at the rear of the machine facing forwardly intothe normal direction of travel.

The disc mower conditioner 10 is provided with a generally conventionalframe 11 mobilely supported over the ground by a pair of transverselyspaced wheels 12 and a draft tongue 14 attached to the tractor (notshown), as is known in the art. Rotational power is delivered from thetractor (not shown) to the disc mower conditioner 10 by a power-take-off(PTO) shaft 16 rotatably coupled with the tractor in a conventionalmanner. As is known in the art, the draft tongue 14 is pivotallyconnected to the implement frame 11, the pivotal movement thereof beingcontrolled by a hydraulic cylinder 19 interconnecting the tongue 14 andthe frame 11. Through manipulation of the hydraulic cylinder 19, thedisc mower conditioner 10 can be moved between a transport positionbehind the tractor and an operative position outboard to the right ofthe tractor so that the disc mower conditioner 10 can be operatedwithout the tractor (not shown) running over the standing crop.

The frame 11 supports a crop harvesting header 20 suspended therefrom bya flotation mechanism 22 so that the header 20 can move verticallyrelative to the frame 11 to enable the header 20 to follow groundundulations and to allow the header 20 to be raised into an elevatedtransport position. The header 20 rotatably supports a conditioningmechanism 25, preferably in the form of a pair of intermeshingconditioning rolls 26 that receive severed crop therebetween andconditions the severed crop material. The conditioning rolls 26discharge the crop material rearwardly into a pair of laterally spacedwindrow shields 28 that consolidate the severed and conditioned cropinto a windrow formed behind the implement 10.

A header lift mechanism 30 is provided to effect the vertical movementof the crop harvesting header between the raised transport position andthe lowered operative position. The lift mechanism 30 includes ahydraulic cylinder 32 associated with each respective laterally spacedthe wheel arm 13 pivotally interconnecting each respective wheel 12 andthe frame 11. The hydraulic lift cylinders 32 interconnect therespective wheel arms 13 and the frame 11 such that an extension of thelift cylinders 32 effects a raising of the frame 11 relative to theground engaging wheels 12. Since the header 20 is suspended from theframe 11, the header 20 is also raised into an elevated transportposition.

Referring now to FIGS. 3-6, the transport latch mechanism 40 for lockingand unlocking the lift mechanism 30 can best be seen. The transportlatch mechanism 40 includes a lock link 42 pivotally connected to thewheel arm 13 and movable between a locking and unlocking position. Whenin the locking position, as shown in phantom in FIG. 3 and in solidlines in FIGS. 4-6, the lock link 42 is engageable against a stop 44affixed to the frame 11 to prevent the frame 11 from further lowering tothe operative position. When retracted back to the unlocking position,as shown in solid lines in FIG. 3 and in phantom in FIG. 4, the locklink 42 clears the stop 44 allowing the frame 11 to freely move betweenthe raised and lowered positions.

The biasing lever 45 is attached to the pivot pin 46 securing the locklink 42 to the wheel arm 13. The biasing lever 45 can be positioned tobias the lock link 42 toward either the locking or unlocking positions.The biasing lever 45 pivots in a hole in the pivot pin 46. An extensionspring 47 is connected to the biasing lever 45 and the lock link 42. Thebiasing lever 45 positions the extension spring 47 in a position toapply a force to either bias the lock link 42 toward the stop 44, andtherefore the locking position, or away from the stop 44, and thereforein the unlocking position. The movement of the biasing lever 45 from oneposition to the other places the spring 47 in an over center orientationto keep the lock link 42 in the desired position irrespective of themovements undertaken by the frame 11.

Referring specifically now to FIGS. 5 and 6, the pivotable lock link 42can be positioned to move into the stop 44 and the corresponding lockedposition, as depicted in solid lines. The biasing lever 45 is manuallypositioned toward the stop 44 by pivoting it about its seat on the pivotpin 46. The extension spring 47 is then applying force to pull the locklink 42 towards the stop 44. When the implement frame 11 is raised byextending the lift cylinders 32, the lock link 42 is pulled by thespring 47 against the stop 44.

As depicted in phantom in FIG. 5, the lock link 42 pivots around andslides past the stop 44 as the stop 44 moves vertically with theextension of the lift cylinders 32 and lodges against the frame 11beneath the stop 44 as the frame 11 moves into the transport position.As shown in FIG. 6, the stop 44 then rests against the lock link 42,which is held against the frame 11 by the spring 47, and preventsfurther lowering of the frame 11. An engaging force is maintained on thelock link 42 by the extension spring 47 after the link 42 is engaged bythe stop 44. The stop 44 rests on the lock link 42 when the liftcylinder 32 is retracted to lower the frame 11, as shown in FIG. 6. Theframe 11 is held in the up or transport position by the lock link 42.

To disengage the lock link 42 from the stop 44, the biasing lever 45 ispivoted away from the stop 44 as shown in solid lines in FIG. 3 and inphantom in FIG. 4. When the lift cylinder 32 is extended to raise theframe 11 off the lock link 42, the lock link 42 is moved away from thestop 44 due to the force of the extension spring 47 biasing the locklink 42 for movement away from the frame. The spring 47 holds the locklink 42 away from the stop 44 so that the frame 11 can be lowered whenthe lift cylinder 32 is retracted.

Accordingly, the lock link 42 is biased toward the latched lockingposition by the pivoted biasing lever 45 and the extension spring 47.The lever 45 positions the spring 47 to pull the lock link 42 intoengagement with the stop 44. The spring 47 is effective to bias the locklink 42 both before the link 42 engages the stop 44 and afterengagement. The latter ensures that the link 42 will not disengage fromits unlocking position to inadvertently engage the stop 44 and besubjected to substantial impact loads, or allow the implement 10 to dropand cause damage thereto. The lock link 42 automatically engages ordisengages from the stop 44 when the biasing lever 45 is positioned inone of the other positions. The operator does not have to dismount fromthe tractor (not shown) to either engage or disengage the latchmechanism 40. The added ease of use will encourage the use of thetransport latch mechanism 40.

Referring now to FIGS. 7-12, a mower conditioner 110 having analternative embodiment of the header lift linkage 140. The draft tongue114 is pivotally mounted in the center of the frame 111 to permitoperative movement of the harvester 110 outboard of the tractor (notshown) to either side thereof. The tongue swing cylinder 119 effectsmovement of the tongue 114. The header 120 is pivotally supported fromthe frame 111 for vertical flotational movement relative thereto.Flotation of the header 120 is assisted by the header flotation springs122. The header 120 can be lifted into a raised transport position bythe hydraulic lift cylinders 132 that operate to raise the frame 111relative to the ground engaging wheels 112 pivotally supported from theframe 111 by wheel arms 113.

Referring now to the enlarged elevational views of FIGS. 8-12, thedetails of the header lift mechanism 130 can best be seen. The header120 is supported on the header lift arms 134 to which the headerflotation springs 122 are attached. The wheel arms 113 are pivotallyconnected to the frame 111 by a wheel arm pivot 138 such that anextension of the lift cylinders 132 effects an articulation about thewheel arm pivot 138 as a result of the increased distance between therespective ends of the wheel arm 113 and the top of the frame 111.

The lift linkage 140 includes an inverted U-shaped strap 142 affixed tothe side of the header lift arms 134 to be engageable with the wheel armpivot 138 which terminates in a cantilevered fashion outwardly from theframe 111 in alignment with the strap 142 being positioned above thewheel arm pivot 138. As the header 120 lowers in its flotationalmovement relative to the frame 111, the header lift arms 134 also loweruntil the strap 142 engages the wheel arm pivot 138. Accordingly, theengagement of the strap 142 with the wheel arm pivot 138 serves as thelower flotation limit for the header 120.

A cam mechanism 145 is mounted to the frame 111 and positioned above thestrap 142. The cam mechanism 145 includes a cam plate 146 pivotallysupported on the frame 111 and an actuator arm 147 pivotally connectedto the cam plate 146 in an offset manner to the pivotal connectionthereof with the frame 111 and also pivotally connected to the pivot pin148 upon which the header lift arm 134 is mounted from the wheel arm113. As the lift cylinder 132 extends to articulate the pivotalconnection between the wheel arm 113 and the frame 111, the fixed lengthactuator arm 147 causes a pivotal motion of the cam plate 146 in such amanner that the cam plate 146 shortens the distance between the camplate 146 and the wheel arm pivot 138 to trap the strap 142therebetween. As a result, the header flotation is substantially lockedout and the header 120 is secured by the time the header 120 reaches thetransport position.

In the normal operating position as shown in dotted lines in FIG. 11,the strap 142 mounted to the side of the header lift arm 134 movesbetween the wheel arm pivot 138, which serves as the lower flotationlimit, and the retracted cam plate 146, which serves as the upperflotation limit. Accordingly, the combination of the wheel arm pivot 138and the retracted cam plate 146 defines the operating range for theflotation of the header 120. By rotating the cam plate 146 throughoperation of the actuator arm 147, the operating range reduces tosubstantially zero as the strap 142 becomes trapped between the pivot138 and the rotated cam plate 146. The cam mechanism 145 serves a dualpurpose as an upper flotation limit and a device to secure the header120 from bouncing during transport.

One skilled in the art will readily recognize that the cam plate 146preferably will not be designed to wedge the strap 142 between the camplate 146 and the wheel arm pivot 138 as the header 120 should bepermitted a slight flexible movement and not be rigidly secured to theframe 111. While the distance between the cam plate 146 and the wheelarm pivot 138 should be minimal to prevent the header 120 from bouncinginto the draft tongue 114, this distance should not be completelyeliminated.

It will be understood that changes in the details, materials, steps andarrangements of parts which have been described and illustrated toexplain the nature of the invention will occur to and may be made bythose skilled in the art upon a reading of this disclosure within theprinciples and scope of the invention. The foregoing descriptionillustrates the preferred embodiment of the invention; however,concepts, as based upon the description, may be employed in otherembodiments without departing from the scope of the invention.Accordingly, the following claims are intended to protect the inventionbroadly as well as in the specific form shown.

Having thus described the invention, what is claimed is:
 1. In apull-type harvester having a frame; a crop harvesting header supportedfrom said frame and being movable between a raised transport positionand a lowered operative position; a lift mechanism for effectingmovement of said header; a header flotation mechanism for assisting aflotational movement of said header relative to said frame within arange of movement proximate to said lowered operative position, animprovement to said flotation mechanism comprising:a lower flotationstop preventing said header from moving below a lower flotation limit;and a cam mechanism defining an upper flotation limit, said cammechanism including a cam plate being movable from a first rotatedposition in which said upper flotation limit is set to define a maximumrange of flotational movement and a second rotated position in whichsaid upper flotation limit is set to reduce the range of flotationalmovement to substantially zero movement.
 2. The pull-type harvester ofclaim 1 further comprising a pair of laterally spaced wheel arms, eachof which is pivotally connected to said frame and rotatably supports aground engaging wheel, said lift mechanism operably interconnecting atleast one of said wheel arms and said frame to induce an articulatedmotion therebetween to effect movement of said header between saidtransport and operative positions, said cam mechanism further includingan actuator arm interconnecting said at least one wheel arm and said camplate to effect movement of said cam plate between said first and secondpositions in response to the articulated motion of said at least onewheel arm.
 3. The pull-type harvester of claim 2 wherein said cam plateis pivotally mounted on said frame for movement between said first andsecond positions.
 4. The pull-type harvester of claim 3 wherein saidheader is mounted on a pair of laterally spaced header lift armspivotally supported from a corresponding one of said wheel arms, saidlower flotation stop being a strap attached to at least one of saidheader lift arms to be engageable with a pivot pin pivotally connectingthe corresponding wheel arm to said frame for articulated movement. 5.The pull-type harvester of claim 4 wherein said cam plate is operable tosecure said strap between said cam plate and said pivot pin when saidcam plate is rotated to said second position.
 6. A mower conditionercomprising:a frame mobilely supported by a pair of laterally spacedground engaging wheels, each said wheel being pivotally connected tosaid frame by a wheel arm; a crop harvesting header forwardly supportedfrom said frame and being movable between a raised transport positionand a lowered operative position, said header being mounted on a pair oflaterally spaced header lift arms pivotally connected to a correspondingsaid wheel arm; a lift mechanism supported by said frame to be operableto effect movement of said header between said transport and operativepositions, said lift mechanism being operable to effect an articulationbetween said wheel arms and said frame to raise said header to saidtransport position; a header flotation mechanism for assisting aflotational movement of said header relative to said frame within arange of movement proximate to said lowered operative position, saidheader flotation mechanism including:a lower flotation stop preventingsaid header from moving below a lower flotation limit; and a cammechanism defining an upper flotation limit, said cam mechanismincluding a cam plate pivotally mounted to said frame and being movablefrom a first rotated position in which said upper flotation limit is setto define a maximum range of flotational movement and a second rotatedposition in which said upper flotation limit is set to reduce the rangeof flotational movement to substantially zero movement.
 7. The mowerconditioner of claim 6 wherein said cam mechanism further includes anactuator arm interconnecting one of said wheel arms and said cam plateto effect movement of said cam plate between said first and secondpositions in response to the articulated motion of said at least onewheel arm, said actuator arm moving said cam plate into said secondposition whenever said wheel arm is articulated to moved said headerinto said transport position.
 8. The mower conditioner of claim 7wherein said lower flotation stop is formed as a strap attached to atleast one of said header lift arms to be engageable with a pivot pinpivotally connecting a corresponding one of wheel said arms to saidframe for articulated movement, said cam plate being operable to securesaid strap between said cam plate and said pivot pin when said cam plateis rotated to said second position.